Only Drawback Of The Oleander Is Poisonous Sap

April 27, 1985|By Elvin McDonald, King Features Syndicate

Oleander is one of the showiest, most satisfactory of all shrubs or small trees, with fragrant flowers possible three seasons out of four. What's more, it blooms best in baking sun, heat that would spell doom to lesser plants, survives protracted drought and is able to do all this in meager sandy soil.

In fact, it seems oleander is perfectly suited to increasing numbers of us, despite one persistent fault: The sap contained by all parts of the plant is poisonous, although the national Oleander Society advises that this is too bitter for man or beast ever to ingest it. In any event, wieners roasted on oleander sticks are said to be lethal and all prunings must be disposed of with extreme care, never burned as inhaling the smoke could also be disastrous.

On the brighter side, in Israel, where oleander has been cultivated since the days of the Bible, controlled amounts of the toxin, known as oleandrin, have been used medicinally in the treatment of skin disorders, as heart stimulants, and to combat deadly snake bites.

Oleander needs to be cold and dry during the winter, but protected against hard freezing and extreme dryness. When spring brings increasing light and warmth, repotting can be done, to a size larger pot; or root and top prune, saving stem clippings for cuttings, and return to the same container, filling in with fresh soil (equal parts packaged all-purpose potting mix, clean, sharp sand and peat moss or well-rotted compost).

When an oleander drops excessive amounts of foliage in the spring and summer, check for possible stagnation in the container or garden, from trapped water unable to drain off. Or, conversely, the roots may need more moisture and air; in other words, a larger container or better preparation and maintenance of the surrounding earth.

Standard or tree-form oleanders are seen increasingly in the retail market. These make superb container plants outdoors in warm weather, inside when frost threatens. They can also be used year-round as indoor trees, where sun shines directly on the leaves at least half a day. Bloom is not likely unless direct sun is received multidirectionally, as in a greenhouse or bay window.

Oleanders grown soft, in constantly moist, rich soil, warmth and moderate light, may be acceptable as leafy specimens, but they will not bloom. Flowering occurs as part of a definite cycle that contrasts ''fat'' and ''lean'' conditions: Spring and summer mean sunny, warm and soil moist to damp, with applications of 5-10-5 or similar fertilizer. Fall and winter mean cool but frostfree, less light, soil on the dry side, and no fertilizer.